Can a power station run your gas boiler in a power cut?
Most British homes lose their heating in a power cut even though the gas is still on. The boiler burns gas, but it needs electricity for the fan that feeds the burner, the pump that moves hot water round the radiators, the ignition and the controls. Cut the power and it stops.
The good news is that those electrics are a small load. Vaillant's installation manual lists its ecoTEC plus combis at 35 W minimum and 80 to 120 W maximum, with under 2 W on standby, and Worcester Bosch's published data for the Greenstar 4000 gives 39 W at full load. That is less than a television: on this model a 1,056 Wh Anker SOLIX C1000 keeps it going for about 12 h 23 min. The catch is getting the power to the boiler safely, and getting the boiler to accept it.
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How long it would run
This model assumes 85 W while firing and firing 60% of the time, as a boiler does on a cold day with the heating on. A milder day, a lower thermostat or a boiler that modulates down to its minimum all make it last longer.
| Station | Capacity | Boiler alone, from full |
|---|---|---|
| EcoFlow DELTA 3 Plus | 1,024 Wh | 12 h |
| Anker SOLIX C1000 | 1,056 Wh | 12 h 23 min |
| Jackery Explorer 1000 v2 | 1,070 Wh | 12 h 45 min |
| Bluetti AC180 | 1,152 Wh | 13 h 17 min |
| Jackery Explorer 2000 Plus | 2,042 Wh | 22 h 50 min |
These are modelled figures for the boiler's electrics running alone, including the station's own conversion losses. Other loads share the same battery, so check each one with the calculator.
Problem one: the boiler has no plug
A boiler is normally wired into a switched fused spur on the wall, not a socket, so there is nothing to plug into the station. Some owners have an electrician replace that connection with a plug and a dedicated socket, or fit a proper changeover arrangement, so the boiler can be moved to a station in an outage. That is a job for a qualified electrician. Do not cut the flex and fit a plug yourself, and never feed a station's output back into a wall socket to power the house wiring.
Problem two: the boiler may refuse to light
Modern boilers prove the flame is lit by passing a tiny current through it to earth. Mains electricity in a British house has its neutral tied to earth, so that works. Most portable power stations have a floating output, where neutral is not tied to earth, and some boilers then fail to detect the flame, lock out and show an ignition fault. Whether yours does depends on the boiler. Some owners report theirs lights on a station; others need the neutral and earth bonded at the supply, which again is only for an electrician to arrange.
Problem three: clean power
Boiler electronics expect a clean sine wave. Lithium power stations generally produce one, but check the specification says pure sine wave before relying on it. Cheap modified-sine inverters are the wrong tool.
What else to keep in mind
- Hot water comes with it. A combi heats water on demand, so if the boiler runs, the taps run hot too.
- System and regular boilers often have a separate pump and controls on a different circuit, so the boiler alone is not the whole load. Your heating engineer can tell you what needs power.
- Wireless thermostats run on batteries, but their receiver is usually powered from the boiler's supply. If the boiler runs, the receiver normally does too.
- Keep a carbon monoxide alarm with a battery in every room with a fuel-burning appliance. It matters more, not less, when you are improvising in a power cut.
- Read the power cut essentials list for the cheap kit, the power-cut guide for the rest of the plan, and the cold-weather guide for what low temperatures do to the battery itself.
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